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Study Suggests Bioelectricity Could Be More Efficient than Ethanol to Power Vehicles

May 7, 2009

MERCED, Calif. - Concerns over petroleum gas prices and
long-term effects of greenhouse gas emissions on the environment
have prompted scientists to look for alternative renewable energy
sources for transportation use. One of the questions at hand is
determining what that preferred technology should be.

Scientists are examining biomass - plant matter that’s grown and
used to generate energy - as a potential power source. Two biomass
technologies involve ethanol and electricity. Biomass converted
into ethanol, a corn-based fuel, can power internal combustion
vehicles. Biomass converted into electricity can fuel a vehicle
powered by an electric battery.

A study by University of California, Merced, Assistant Professor
Elliott Campbell and two other researchers in the online edition of
this week’s Science journal suggests that biomass used to generate
electricity could be the more efficient solution.

In the study, Campbell, along with Christopher Field, director
of the department of global energy at the Carnegie Institution and
David Lobell of Stanford University, the scientists found that
biomass converted into electricity produced 81 percent more
transportation miles and 108 percent more emissions offsets
compared to ethanol.

In other words, said Campbell, vehicles powered by biomass
converted into electricity “got further down the road” compared to
ethanol. As a result, Campbell continued, “we found that converting
biomass to electricity rather than ethanol makes the most sense for
two policy-relevant issues, transportation and climate.”

The scientists based their study on two criteria: miles per area
cropland and greenhouse gas offsets per area cropland. In both
cases, scientists considered a range of feedstock crops, focusing
primarily on corn and switchgrass and four vehicle types: small
car, midsize car, small SUV and large SUV. Switchgrass is a
perennial grass native to North America and is a good feedstock
crop to grow as biomass because it is resistant to many pests and
plant diseases and it is capable of producing high yields with very
low applications of fertilizer.

First, they looked at how many miles a range of vehicles powered
by ethanol could travel versus a range of electric vehicles fueled
by electricity. Second, they examined offsets to greenhouse gas
emissions for ethanol and bioelectricity. Land use is an important
factor to consider when evaluating each method. Globally, the
amount of land available to grow biomass crops is limited. Using
existing croplands for biofuels could cause increases in food
prices and clearing new land, or deforestation, can have a negative
impact on the environment.

The authors are careful to point out their study looked at two
criteria, transportation and greenhouse gas offsets, but did not
examine the performance of electricity and ethanol for other policy
relevant criteria.

“We also need to compare these options for other issues such as
water consumption, air pollution and economic costs,” Campbell said.

Campbell joined UC Merced as an assistant professor in the
School of Engineering in 2008. He earned bachelor’s and master’s
degrees at Stanford University and his Ph.D. from the University of
Iowa. Prior to joining UC Merced, Campbell received national
attention for another study that concluded the United States Could
meet up to 6 percent of its energy needs with biofuels produced on
abandoned or degraded agricultural land.

A copy of Campbell’s abstract can be viewed online at

Media Contact:

Donna Birch Trahan

UC Merced Office of Communications


UC Merced opened September 5, 2005, as the 10th
campus in the University of California system and the first
American research university of the 21st century. The campus
significantly expands access to the UC system for students
throughout the state, with a special mission to increase
college-going rates among students in the San Joaquin Valley. It
also serves as a major base of advanced research and as a stimulus
to economic growth and diversification throughout the region.
Situated near Yosemite National Park, the university is expected to
grow rapidly, topping out at approximately 25,000 students within
30 years.